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June 10, 2011

Yo-Yo Dieting Healthier Than Obesity?

by Sam Savage

(Ivanhoe Newswire) -- In a recent study comparing lifelong obesity to the weight fluctuations of "yo-yo dieting," it is suggested that it's better to attempt to lose weight than to not diet and stay obese.

"It is clear that remaining on a stable, healthy diet provides the best outcome for health and longevity," which the study's principal investigator, Edward List, PhD, a scientist at Ohio University, Athens, was quoted as saying.

"However, obese individuals commonly weight cycle "” they have repeated intentional weight loss followed by weight regain, often called yo-yo dieting. While yo-yo dieting is thought to be harmful, there is little hard scientific evidence to support that."

In order to verify the long-term health effects of yo-yo dieting, List and his collaborators performed what they call "the first controlled study of a yo-yo diet regimen used for an entire life span" with the aid of mice.

Thirty mice, in groups of 10 each, received one of three diets: high fat, low fat or a yo-yo diet, consisting of four weeks of the high-fat diet followed by four weeks of the low-fat diet. The mice stayed on their respective diets throughout their life span. Measures of health, including body weight, body fat and blood glucose (sugar) levels, were obtained.

List said the yo-yo diet resulted in considerable fluctuations in these health measures, decreasing during the low-fat diet and increasing to a diabetic state during the high-fat diet. When health measures during the high-fat and low-fat diet regimens of the yo-yo diet group were averaged, their "average health" was improved compared with obese mice that stayed on the high-fat diet, he reported. Compared with the mice fed the high-fat diet, mice on the yo-yo diet lived virtually 35 percent longer.

"Surprisingly, the mice on the yo-yo diet had a similar life span to that of the low-fat-fed group," List concluded.

"The fear of negative health consequences due to weight cycling may be overemphasized. From our study, it appears that it is better to continue to encourage weight loss regardless of the number of attempts and failures."